It cost the Rand Corporation millions of dollars to discover this: Teens who watch too much sex on TV have too much sex and get pregnant more than kids who don't.

No surprise there.

But what is surprising is that we parents are often more embarrassed to talk about sex than our kids. We think little of pressing them about school, grades, athletics, colleges and careers, yet we dance around this elephant in every room of our homes.

Why?

I...